Currently, a prior art backlight module generally includes a backboard, a plastic frame and an optical film. The optical film is disposed within a receiving space located within the backboard. The plastic frame is defined with a retaining hole to engage with a hook so as to attach the plastic frame onto the backboard. The plastic film will press upon the optical film so as to securely position the optical film within the receiving space.
While the dimension of the display panel becomes larger and larger, the dimension of the backboard, the plastic frame, and the optical film become larger and larger. In comparison, the longer the plastic frame, the more the retaining holes are required. During the assembling, transportation, and utilization of the backlight module, different portion of the plastic frame may also withhold different stress. There is a very high possibility of separation between the retaining holes of the plastic frame and the hook of the backboard. Once a separation between the plastic frame and the backboard is encountered, the optical film will become loose, and a leakage of the light from the backlight module will also be encountered.